What would be the treatment of the commission given to an employee in addition to the regular compensation received from the same employer (income payor/withholding agent)? Is the remittance of the withholding tax on commission separate from the tax withheld on compensation?

The commission received from the same employer shall be considered as supplementary income. It shall be added to the regular compensation subject to income tax and consequently to withholding tax using the withholding tax table on compensation, The tax withheld shall be filed month and remitted using BIR Form No. 1601-C.